1. Field of the Invention
The invention relates to a magnetic recording medium, particularly to a magnetic recording medium that can be favorably used in a magnetic recording system using an MR head as a reproduction head.
2. Description of the Related Art
Use of an inductive MR composite thin film head using an MR head as a reproductive head has been proposed in compliance with recent requirements of high density recording for magnetic recording media, The MR head is a reproduction head for sensing data by taking advantage of an MR (magnetoresistive) effect. Since this head has higher sensitivity than conventional heads and reproduction output thereof can be largely improved, a high density recording is possible in a magnetic recording system using the MR head as described above even in a magnetic recording medium having a small leak magnetic flux ascribed to a short recording wavelength.
However, since the MR element part of the MR head comprises a laminated thin layer, the MR head is liable to be damaged by direct sliding contact with a tape as well as by generation of smearing and electrostatic discharge (ESD) as compared with the inductive head. “Smearing” as used herein refers to as a phenomenon by which a metal surrounding the MR element is elongated in the sliding direction due to ductility of the metal to cover the MR element, and “ESD damage” refers to as a phenomenon by which the MR head is deteriorated or the MR head and peripheral portion thereof are melted by a heat generated by electrostatic discharge. When the head is damaged by these phenomenon and generation of flaws, the output of the MR element becomes unstable due to resistance changes of the MR head or the head does not substantially function, causing system faults in both cases.
For enabling a long term use of the MR head, the length of the MR head in the direction of depth has been increased in order to enable the function of the head to be maintained even when the head suffers a certain extent of abrasion. However, since sensitivity of the MR element decreases by the countermeasures as described above, it is a problem that the MR head is forced to be used with a low reproduction output.
Accordingly, in a desirable technology, defective output and defective reading ascribed to the damages of the head after a long term of use may be prevented from occurring by reducing the degree of abrasion caused by sliding while maintaining high sensitivity of the MR head by improving the magnetic tape side instead of improving the MR head side. Sensitivity of the MR head would be enhanced by reducing the length of the MR head in the direction of depth with no changes of the output resistance by abrasion provided that the MR head is not worn by sliding contact of the tape. Such technology is considered to be applicable for improved high density recording.